Detonation flame arrestor including a transition point/attenuation matrix and torturous path media

ABSTRACT

A detonation flame arrestor including an outer cylinder, an inner cylinder, transition point/attenuation matrix and tortuous path media. The inner cylinder is secured to a canister flange and positioned inside the outer cylinder secured to the canister flange, altogether forming a canister. The torturous path media is positioned in the canister between the inner cylinder and the outer cylinder to to provide turbulence and a large surface area which acts as a heat sink to extinguish a flame. Both the outer cylinder and the inner cylinder include a transition point/attenuation matrix which forms their respective cylindrical circumferences. Helical or parallel wire or rings create the transition point/attenuation matrix which attenuates and creates turbulence as the first stage of quenching a flame front.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to the field of detonation flame arrestors in flammable vapor pipe line applications.

2. Background of the Invention

Three elements must be present in order for a flame to occur, oxygen, heat (ignition), and a flammable vapor. In a flammable vapor piping system application, which would benefit from the detonation flame arrestor apparatus of the present disclosure, the flammable vapor is flammable gas which mixes with the oxygen introduce from air or other process. If the flammable gas mixes with the oxygen within the LEL and UEL (explosive limits) of the gas, and if/when subjected to an ignition source, a flame will result. If the three requirements remain available, the flame will continue and travel along the piping system with catastrophic consequences. In a stationary flammable mixture, a flame appears to travel toward the unburned gas. This apparent motion is known as flame propagation. Flames generally propagate much faster in piping systems than in the open atmosphere. In addition, flames in piping systems typically propagate upstream against the flow of gas toward its source. However, flames will propagation in any direction as long as the piping system contains a gas/oxygen mixture that is within explosive limits of the gas. This flame propagation usually starts out moving at subsonic velocities called “deflagration”. If/and/or pipe length or ignition source is sufficient, the deflagration will transition to supersonic velocities known as a “detonation” and “over-driven detonation” (or “stable detonation”). Other phenomena, like a pipe restriction, debris, varied piping configurations, lightning and more can cause this transition from deflagration to detonation in a shorter length of piping. A purpose of a detonation flame arrestor is to remove heat from the flame front, dropping the temperature below to a point to where the flame cannot be sustained, thereby stopping or arresting it at the point of the detonation flame arrestor along the length of the piping system. It is most desirable if the detonation flame arrestor is capable of doing this regardless of the direction of travel of the flame front and the distance between the detonation arrester and the ignition point. The ability for a detonation flame arrester to arrest the propagating flame front relies on the ability to maintain high temperature differential between the flame front and the detonation flame arrester's element and the elements ability or efficiency as a heat sink. An ideal element design has high transfer rate per in3 of element matrix while maintaining a low pressure drop for the process gas flow.

A detonation is generally defined as a flame front moving at or above the speed of sound. Detonation entails increased compression of the mixture of oxygen and flammable gases by a pressure front (shock waves) which travel in front of the flame. A detonation may have, for example; 40% hydrogen with 34% oxygen mixture when ignited can have a velocity in the range of 2,450 m/s and dynamic pressure front of 2,000 lbs./in2, with DP/Po of 101.3 using 19.7 lbs./in2 initial pressure. The shock waves resulting from the detonation travel the length of the piping system and are reflected back if there is a restriction in the line.

A detonation flame arrestor is designed to extinguish a flame front resulting from an explosion or detonation of the gas mixture in the line. However, in addition to extinguishing the flame, the flame arrestor must be capable of dissipating (attenuating) the pressure front that precedes the flame front. The pressure front (shock wave) is associated with the propagation of the flame front through the unburned gas toward the flame arrestor. The flame induced pressure front is always in the same direction as the propagating flame travel. The pressure rise can range from a small fraction to more than 100 times the initial absolute pressure in the system.

Known flame arrestor apparatuses commonly comprise flame extinguishing plates, ribbon and/or some type of spherical or packed bed media which includes very small gaps of a small diameter (typically at or around the MESG of gases) media with passages that permit gas flow, but prevent flame transmission by extinguishing combustion. This results from the transfer of heat from the flame to the plates, ribbon and/or spherical or packed bed media which effectively provides a substantial heat sink. This heat sink removes one of the required elements for a flame, heat, there by extinguishing the flame.

Three very common flame arrestor element designs are a crimped ribbon type such as described in U.S. Pat. Nos. 4,909,730, 5,415,233 and 6,644,961, parallel plate type as described in U.S. Pat. No. 5,336,083 and Canadian Patent No. 1,057,187, as well as spherical or packed bed media type described in U.S. Pat. No. 5,336,083. The first two above designs are referred to as straight path flame arrestors because the gas flow takes a straight path from the channel entrance to the exit.

Flame arrestors are often used in installations where large volumes of gas must be vented with minimal back pressure on the system. It is generally understood that even small deviations in channel dimensions can compromise flame arrestor performance.

A known significant conflict in flame arrestor design results from the fact that gas line pressure is frequently maintained at atmospheric pressure or higher. Pressure drop resulting from gas passage through a flame arrestor, or back pressure created as a result of gas passage through the flame arrestor, are undesirable. However, pressure drop resulting from passage of a flame through the plates, ribbons, or spherical or packed bed media in the flame arrestor assists in effectively extinguishing the flame. This is because the pressure drop increases the “Residence time” (the average amount of time that a particle spends in a particular system) of the flame passing through the media which results in an increase in heat transfer thus removing the high temperature requirement for the flame to propagate. The extinguishing process (flame arrestment) is based on the drastic temperature difference between the flame and the media material. As such, this is a process that not only depends on the temperature gradient, but also on the hydraulic diameter of the passages and the thermal conduction properties of the gas and the media. As a result, a need, therefore, exists for a detonation flame arrestor design which includes a large pressure drop per unit volume but a small aggregate pressure drop over the entire apparatus.

The level of turbulence significantly affects the rate of heat loss of the flame within the flame arrestor passages/media. Turbulence is desirable to facilitate the level of heat loss within the flame arrestor by increasing “Residence time”. However, straight path flame arrestors of the currently known designs are inefficient in maximizing the amount of turbulence for effective flame arrestment. This is partly because the path of the flame front is unaltered through the flame arrestor. Most commonly, the element is designed so that the gas flows over the surface area of the parallel plates or crimped ribbon so that in the event of a flame front heat transfer will occur so as to extinguish the flame. This flow of gas over the media is most commonly laminar in an effort to reduce the pressure drop through the element. Prior art U.S. Pat. No. 5,415,233, incorporated herein by reference, utilizes a mechanism for increasing turbulence, but the first 20% of the element length is laminar flow with no turbulent flow at all and less than 2% is in the form of turbulent creating sections that add minimal turbulent flow inside the remaining 78% of the laminar flow crimp ribbon sections. In addition, known straight path flame arrestor designs are inefficient in dispensing the initial shock wave or reflective shock wave. A need exists for a flame arrestor design which alters the flow of the flame front as it passes through the flame arrestor.

Straight path flame arrestors of the currently known designs include retaining bars or support mechanisms which are heavily built of significant mass and strength in order to withstand the high explosion pressure of a detonation. These significant structures add a substantial amount of weight and cost to the device and require extra care to be taken in order to support the piping and the detonation flame arrester. A need exists for a flame arrestor design that is less expensive to construct and lighter in weight.

In addition, the spherical or packed bed media commonly used for detonation flame arrestors are commonly comprised of ceramic beads. Although ceramic beads have useful thermal characteristics, they are relatively fragile and cannot be compacted without being crushed. Compaction is highly desirable in order to minimize the space between adjacent beads, thereby maximizing surface area of the spherical or packed bed media and varying the path of travel of the flame (creating turbulence). A further concern is that the ceramic media could also be crushed by the shock wave thereby leaving gaps larger than the Maximum Experimental Space Gap (MESG) of the gas which would compromise the performance (flame stopping capabilities) of the flame arrestor. Moreover, All spherical or packed bed media may not pack correctly when the device is loaded (filled), this is referred to as bridging and devices have been designed in an attempt to overcome this potentially disastrous problem, particularly on large systems (see U.S. Pat. No. 5,247,970, for example). It is difficult in small devices like flame arresters to ensure that the media is randomly packed correctly. This so called bridging can and will collapse or settle and produce a gap in the media sufficient enough for the device to allow a flame to pass un-arrested and thereby allow a catastrophic failure to occur in the system. To compensate, some Detonation Flame Arrester standards require the production element to be built 50% larger than a tested element. This brings the cost and size of the units up substantially. A need, therefore, exists for a flame arrestor which can be built so as to consistently maintain the correct hydraulic diameter while maximizing surface area, thereby maximizing the heat sink properties of the media as well as increase turbulent flow through the spaces between adjacent components of the media.

Prior art constructions have also been known to fail due to the pressures encountered in connection with a reflection pressure front. Although the flame is extinguished within the flame arrestor, a high pressure wave front may exit the outlet side of the flame arrestor as a result of the pressure rise from the initial shock wave. This high pressure wave front continues to travel along the pipe line in the direction of flow. This high pressure wave front, however, will be reflected by any discontinuity located in the pipe line. Discontinuities are the result of bends, stubs, valves, reducers, ice, and the like. As a wave front strikes such a discontinuity, a reflection front is created which travels back towards the flame arrestor. Reflections from many objects along a pipe line can cause transient pressure increases many times the initial pressure. When these reflections enter the outlet side of the flame arrestor, the pressure within the flame arrestor element channels can become many times greater than for which it was designed. While these pressure increases are of extremely short duration and transient in nature (dynamic), they nonetheless are known to cause failures in flame arrestors. Current designs use physical reflectors designed to receive and reflect the shock wave, these work well, however, such reflectors are typically mounted mid-stream (within the gas flow path) and thereby increase the overall pressure drop of the device. A need, therefore, also exists for a flame arrestor that includes the capability of attenuating an initial shock wave and a reflection pressure front, but yet does not cause an increase in pressure drop and can consistently resist damage as a result of high dynamic pressure fronts.

A detonation flame arrestor must also be capable of attenuating a reflective pressure front in addition to the initial pressure front (shock wave). Initial shock waves impacting flame arrestor elements have been known to cause significant structural damage (element breach) causing the flame arrestor element to fail. Prior art designs including media such as crimped ribbon and expanded metal have been known to suffer significant damage after a detonation has hit them. While this damage does not always lead to failure, it is significant enough to warrant replacement of the device. Compression in flame arrestor design is the force exerted on the outside of the cylindrical element toward the center. Tension is the force exerted from the inside of the cylinder toward the outside. Certain detonation flame arrestor designs employ rolled expanded metal. The rolled expanded metal functions to provide a torturous flow of the flame through the elements to provide heat transfer. Such designs are efficient in attenuating a tensive force. In such designs, however, the detonation shock wave may impact the element from the outside causing a compressive force on the rolled expanded metal media. This compressive force has been known to crush the rolled media resulting in curling at the top and bottom sealing surfaces. If the element is not replaced, this curling may result in failure of the element by allowing a flame path around the element media thus avoiding the function of the media. A need exists for a support structure for the media in an expanded metal design so as to resist compressive forces.

Another important factor in flame arrestor design relates to the ability to clean the media. Presently known parallel plate, ribbon, and/or packed bed media designs are known to become blocked or clogged as a result of collection of contaminant particles carried in the gas stream. Once significant clogging occurs, which restricts flow and increases pressure drop, the entire flame arrestor must be removed for cleaning or replacement. Cleaning usually requires the introduction of a solvent to the media in a direction opposite of flow so as to dislodge clogging contaminates or particles. A need exists for a flame arrestor design which can be cleaned in stream and/or easily accessed for cleaning and/or replacement of the element.

Detonation flame arrestors known presently in industrial applications are not known to be effective for low Maximum Experimental Space Gap (MESG) gases, such as Group B gases. In particular, known detonation flame arrestors are not effective for hydrogen gas or enriched oxygen and hydrogen applications. Ribbon or parallel plate detonation flame arrestor constructions cannot be cost effectively produced to meet the requirements of low MESG applications. A need, therefore, exists for a detonation flame arrestor design which can be manufactured in a cost effective manner which is capable of operation in low MESG gas environments.

SUMMARY OF THE INVENTION

The detonation flame arrestor of the present disclosure includes, generally, an outer cylinder secured to a canister flange; an inner cylinder secured to the canister flange and rolled expanded metal or stacked metal cone torturous path media retained between the outer and inner cylinders. Both the outer cylinder and inner cylinder, while being secured to the canister flange on one end, include a domed face on their other end. The outer cylinder, inner cylinder, and canister flange, together form a canister. The canister is secured within an outer housing bolted to a bulkhead which is welded to the inside of the outer housing. The outer housing is then fitted in the flammable vapor pipe line flow path such that the flow of gas passes into the outer cylinder and through the canister or from the inner cylinder through the canister. The outer housing has a removable cover on the top and bottom for cleaning and/or removal and replacement of the complete element canister without the need to remove the entire flame arrester from the pipeline.

Both the outer cylinder and the inner cylinder include a transition point/attenuation matrix which forms their respective cylindrical circumferences. The respective transition point/attenuation matrix's of both the outer cylinder and the inner cylinder include helical or parallel wedge wire or rings, the wire having a tapered surface and a blunt (flat) surface such that the direction of the taper on the outer cylinder circumference points towards the center of the cylinder while the tapered surface of the inner cylinder points towards the outer cylinder, with the blunt surface facing the flow from either pipe flange, the device is bi-directional. The inner cylinder is of a smaller diameter than the outer cylinder such that when the canister is assembled, the inner cylinder fits inside the outer cylinder such that the torturous path media is retained between the tapered surface of the transition point/attenuation matrix of the outer cylinder and the tapered surface of the transition point/attenuation matrix of the inner cylinder.

The domed face of the outer cylinder is pressed onto the torturous path media thereby compacting the media so as to reduce the space between outer and inner cylinders. The torturous path media is tightly bound and has no gaps, and thereby, filling the space between the outer and inner cylinder fully.

The canister is positioned within the outer housing such that a pressure front which passes through the pipeline and into the outer housing impinges upon the domed face of the inner cylinder, the bulkhead and the blunt face of the transition point/attenuation matrix. The detonation wave front is attenuated by the domed face of the outer cylinder and the bulkhead and the blunt face of the transition point/attenuation matrix. Likewise, after the flame front is extinguished by passage through the canister, a reflected pressure front will impinge the underside of the domed face of the inner cylinder and the blunt face of transition point/attenuation matrix and become attenuated. (This process is reversed if the flame front comes from the opposite direction in a bi-directional application).

After the flame front impacts the domed face of the outer cylinder, it must make an abrupt (ninety degree (90°)) turn in order to pass through the transition point/attenuation matrix of the inner cylinder. The gap size between adjacent windings of the transition point/attenuation matrix can be chosen for a particular gas or gas group and acts as the first mechanism for arresting the flame passing there through. The flame then passes through the torturous path media and is further quenched as a result of passing through the torturous path media and contacting the surface of the torturous path media (heat sink). Once the quenched gas exits the torturous path media, it passes through the transition point/attenuation matrix of the outer cylinder which is likewise gapped for a chosen gas or gas group. Once the gas exits the outer cylinder, it must again make an abrupt (ninety degree (90°)) turn twice to continue flow through the pipeline.

Accordingly, flame arrestment is achieved in the detonation flame arrestor of the present invention through the combination of the gaps between adjacent windings of the transition point/attenuation matrix on the inner cylinder and outer cylinder as well as the layered torturous path media. The gap size between adjacent transition point/attenuation matrixes being lower than the MESG of the gas so as to provide the first mechanism for flame arrestment. Layered expanded metal or stacked cones provide a torturous flame path and large heat transfer area between the flame front and the expanded metal media.

This transverse design of the flame arrestor of the present invention serves two very significant functions. First, it allows the shock wave to impact the high strength surfaces of the domed faces of the outer cylinder and the bulkhead and the blunt face of the transition point/attenuation matrix as stated above. The second function is to allow the total surface area (dictated by the length) of the canister to be varied to accommodate a desired pressure drop simply by lengthening the canister as opposed to increasing the diameter as with a straight path design.

In the preferred embodiment, the torturous path media consists of layers (by rolling tightly) of expanded metal (or stacked metal cones). The layered media creates a torturous path through the adjacent media. The blunt face of the transition point/attenuation matrix and the torturous path of the expanded metal media disrupts the laminar flow of a flame front (creates turbulence). Moreover, in addition to increasing turbulence, the fact that the combination of the transition point/attenuation matrix and expanded metal screen means that they have greater surface area than crimped ribbon to create a heat sink so as to extinguish a flame passing there through. Accordingly, increased heat transfer is achieved. The canister, including the torturous path media contained therein, is designed to provide an optimum pressure drop per unit volume to provide maximum flame arrestment. Again, as a result of the transverse design, the aggregate pressure drop resulting from the passage of the gas through the canister can be maintained at a low value by varying the length of the canister as required.

The blunt surface of the wire/ring forming the transition point/attenuation matrix serves the dual purposes of transitioning laminar flow to turbulent flow hence the name “transition point” providing turbulent flow characteristics into the canister and also to provide attenuation and acts as the first mechanism for arresting the flame passing there through. Turbulent flow is created by the blunt side of the wire/ring disturbing normally laminar flow of the gas past. Creating turbulent gas to flow past, improves the heat transfer characteristics by increasing velocity and decreasing pressure of the flame front (akin to flow over an orifice).

Debris trapped between adjacent windings of the tapered surface of the transition point/attenuation matrix can be easily dislodged upon a reverse flow within the canister by injecting a high pressure cleaning solution through the outer and inner cylinders of the canister or by inserting cleaning rod nozzles directly into the torturous path media during construction. If the element is beyond cleaning, it can be removed through the access ports and replaced while the flame arrestor remains flanged between the pipelines. Most prior art requires the replacement of the entire flame arrester at a substantially higher price.

The size of the gaps between adjacent windings of the transition point/attenuation matrix of both the outer cylinder and the inner cylinder acts to extinguish a flame passing there through according to known characteristics of selected gases. Thus, a gap size can be selected depending upon the type of gas to be carried by the application, and secondarily, the transition point/attenuation matrix also serves to contain the torturous path media.

The transition point/attenuation matrix also serves to give needed strength to the entire canister element. Rolled expanded metal alone has shown to distort to failure after being subjected to a detonation, especially when the force is applied to the outside of the cylinder versus inside the cylinder. Other detonation flame arresters rely on bulbous heavily built supports to maintain the integrity of the device as in U.S. Pat. No. 6,644,961 B2. This not required with the transition point/attenuation matrix.

The transition point/attenuation matrix on the inner and outer cylinders can be effectively produced by spiral winding a tapered wire around their respective cylindrical circumferences or by stacking spaced rings. The gap size can be controlled so as to be lower than the published (known) MESG properties of a particular gas or gas group winding the wire/rings around the cylinders can be done economically while maintaining strict tolerances.

It is therefore an object of the present invention to provide a detonation flame arrestor that includes a canister which requires the flame front to make an abrupt direction change to pass through the canister

It is an additional object of the present invention to provide a detonation flame arrestor which includes a transition point/attenuation matrix.

It is a further object of the present invention to create a detonation flame arrestor including a transition point/attenuation matrix on an inner cylinder and an outer cylinder together forming the canister.

It is yet a further object of the present invention to provide a detonation flame arrestor including a transition point/attenuation matrix using a wire which may be tapered on at least one surface so as to trap debris and blunted on at least one side to create turbulence characteristics through the wedge wire screen.

It is a still further object of the present invention to provide a detonation flame arrestor including a transition point/attenuation matrix which also includes a gap between adjacent windings of the transition point/attenuation matrix selected for a particular gas type or gas group.

It is yet an additional object of the present invention to include an torturous path media made from expanded metal or stacked metal cones, between the inner cylinder and outer cylinder to act as a torturous path and heat sink to extinguish a flame passing there through.

It is a yet another object of the present invention to include a blunt surface of the transition point/attenuation matrix to attenuate flow and also to increase the turbulence of the gas/flame passing there through.

It is an object of the present invention to provide a detonation flame arrestor design which is effective for low MESG gas applications.

It is also an object of the present invention to provide a detonation flame arrestor including an inner cylinder and outer cylinder with torturous path media there between which is capable of being cleaned by injecting a high pressure cleaning solution through the inlet and outlets of the device or from within the torturous path media.

It is also an object of the present invention to provide a detonation flame arrestor that's inner cylinder and outer cylinder with an torturous path media there between which is capable of being removed and replaced while still flanged between the pipelines.

Additional objects of the present invention include attenuation of the pressure front and reflective pressure front by designing the flame arrestor to provide a structurally sound domed face on both the outer cylinder and inner cylinder.

Further objects, features, and advantages of the present invention will be apparent to those skilled in the art upon examining the accompanying drawings and upon reading the following description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. is a view of the external housing of the flame arrestor of the present disclosure as it would be installed in a flammable vapor piping system.

FIG. 2 is a side cut-away view taken along line 2-2 of FIG. 3 depicting the detonation flame arrestor of the present disclosure including transition point/attenuation matrix and torturous media.

FIG. 3 is a view of the flame arrestor of FIG. 1 rotated approximately ninety (90°) degrees.

FIG. 4 is a view taken along line 4-4 of FIG. 1.

FIG. 5 is a partial cut-away side view of the outer cylinder of the flame arrestor of the present disclosure depicting helical wedge shaped wire used for the transition point/attenuation matrix.

FIG. 6A is a detail cut-away view depicting the assembly of the helical wedge shaped wire transition point/attenuation matrix of the inner and outer cylinders with expanded metal torturous path media inserted between the inner and outer cylinders.

FIG. 6B is a detail cut-away view depicting the assembly of the helical wedge shaped wire transition point/attenuation matrix of the inner and outer cylinders with stacked metal cone torturous path media inserted between the inner and outer cylinders.

FIG. 7 is a cut-away side view depicting the assembly of the canister with expanded metal torturous path media inserted between the inner and outer cylinders and welded to the canister bottom and bolted to the bulkhead flange.

FIG. 8A is a view depicting a section of expanded metal torturous path media of the preferred embodiment.

FIG. 8B is a top view depicting the shape of the expanded metal torturous path media of the preferred embodiment.

FIG. 9 is a side cut-away view of the detonation flame arrestor of the present disclosure including helical wedge shaped wire forming transition point/attenuation matrix and stacked metal cone torturous media.

FIG. 10 is a cut-away view depicting helical wedge shaped wire as the transition point/attenuation matrix of the inner and outer cylinders and stacked cone torturous metal media inserted between the inner and outer cylinders welded to the canister bottom and bolted to the bulkhead flange.

FIG. 11A is an isometric top view of a section of stacked metal cone torturous media.

FIG. 11B is an isometric bottom view of a section of stacked metal cone torturous media.

FIG. 12 is a side cut-away view of the detonation flame arrestor of the present invention including transition point/attenuation matrix and torturous media with flow direction arrows indicating the flow of gas or flame front as it penetrates the matrix from the side of the outer canister.

FIG. 13 is a side cut-away view of the detonation flame arrestor of the present disclosure including transition point/attenuation matrix and torturous media with flow direction arrows indicating the flow of gas or flame front as it penetrates the matrix from the bottom of the inner cylinder.

FIG. 14 is a cross section illustration depicting turbulent flow as gas hits the blunt face and flows between each helical or parallel wedge shaped wire or ring as the transition point/attenuation matrix of the present disclosure.

FIG. 15 is a cross section illustration depicting turbulent flow as gas hits the blunt face and flows between each helical or parallel quadrilateral shaped wire or ring as the transition point/attenuation matrix of the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An external view of the detonation flame arrestor 10 of the present invention is shown in FIG. 1. Detonation flame arrestor 10 is designed to be placed in line in a gas piping system (not shown) in which the gas line has an inflow end and an outflow end (not shown). FIG. 1 depicts the external housing 16 of flame arrestor 10 which is of a design generally known in the art and includes an inlet flange 12 for connection to the inflow end of the gas line, an inlet port 14, an external housing body 16, an outlet port 18, and an outlet flange 20 for connection to the outflow end of the gas line. External housing body 16 is generally cylindrical and oriented at approximately a forty-five degree (45°) angle from inlet port 14 and outlet port 18. Inlet flange 12 and outlet flange 20 in the preferred embodiment are raised face weld neck flanges known in the industry for flame arrestor service. The external housing body 16 of flame arrestor 10, therefore, provides a substantially hollow pressure vessel shell which is in open internal communication with the gas piping system.

Referring next to FIG. 2 which is a side cut-away view of flame arrestor 10 depicting a canister 32 mounted within external housing 16 of flame arrestor 10. As depicted in FIG. 2, canister 32 is mounted within external housing 16 such that its longitudinal axis is parallel to, and concentric with, the longitudinal axis of external housing 16. This means that the flow pattern through flame arrestor 10 through canister 32 is transverse to the longitudinal axis of external housing 16, and at approximately a forty-five degree (45°) angle from the longitudinal axis of the pipeline. The transverse orientation of canister 32 within external housing 16 means that gas flow into inlet port 14 through inlet flange 12 from the inflow of the gas line passes around canister 32 and is required to take an abrupt turn, approximately 90° in the preferred embodiment, to pass through canister 32 and takes a second abrupt again approximately 90° turn to exit from canister 32 into and through outlet port 18, outlet flange 20 on into the outflow end of the pipeline.

With reference to FIG. 1 in combination with FIG. 2, external housing 16 includes an access port 21 positioned adjacent outlet port 18. Access port 21 provides access to the interior of external housing 16 adjacent outlet port 18 below canister 32. Access port 21 allows access to bolts 44 to enable the removal of canister 32 or also provides access to the interior of external housing 16 for cleaning. Access port 21 is covered by a blank flange 22 in the preferred embodiment which is secured to access port 21 by a plurality of bolts 23 secured by a plurality of nuts 25 so as to securely seal access port 21 against the escape of gas.

External housing 16 also includes in the preferred embodiment a removable cap 24. Cap 24 is secured to external housing 16 by a plurality of bolts 30 secured by nuts 28 so as to provide a seal to prevent the escape of gas. Cap 24 is removable from external housing 16 to provide access to the interior of external housing 16 for cleaning and access to canister 32. For example, Cap 24 may be removed from external housing 16 while blank flange 22 may be removed from access port 21 so that the interior of external housing 16 and particularly canister 32 may be cleaned by flushing with water or more preferably a solvent solution which would flush debris from the interior of external housing 16 and also canister 32 which would drain by gravity out of external housing 16 through access port 21. Alternatively, with cap 24 and blank flange 22 removed, canister 32 may be removed from external housing 16 through the removal of bolts 44 without having to remove external housing 16 from the piping system. Once removed, canister 32 may be cleaned, serviced, or replaced as necessary.

FIG. 3 is an isometric view of the exterior of flame arrestor 10 of the present disclosure depicting external housing 16, inlet flange 12, access port 21 with blank flange 22 secured thereto. FIG. 3 further depicts cap 24 shown secured to external housing 16 by bolts 30.

With reference to FIG. 2 taken in combination with FIG. 7, canister 32 includes an outer cylinder 34, an inner cylinder 36, a canister flange 38, and media 40 retained between inner cylinder 36 and outer cylinder 34. Both outer cylinder 34 and inner cylinder 36 are preferably welded to canister flange 38. A ring-shaped bulkhead 42 is fixed within external housing body 16. In the preferred embodiment, bulkhead 42 is just less in diameter as, and is permanently welded within, external housing body 16.

By way of example, a canister of the following dimensions has been found suitable to arrest a detonation flame in a hydrogen gas environment in a three inch (3″) pipeline application. In the preferred embodiment, outer cylinder 34 and inner cylinder 36 are constructed of T-304 stainless steel in order to resist corrosion, however, it is understood that other metals and alloys are suitable, depending upon the gas environment.

Outer cylinder:

-   -   8″ ID×15″ overall length having a 10″ length of helical wedge         shaped wire screen transition point/attenuation matrix;     -   4″ long×8″ domed face;     -   ½″ long first weld ring;     -   ½″ long second weld ring;

Inner cylinder:

-   -   4¼″ OD×13¼″ overall-length having a 10″ length of helical wound         wedge wire screen transition point/attenuation matrix;     -   2½″ long×4″ domed face;     -   ⅜″ long first weld ring;     -   ⅜″ long second weld ring;     -   ½″ thick canister flange, approximately 8½″ diameter.         It is understood that this is an example only as other sizes and         dimensions as well as other gas environments are contemplated.

Bulkhead 42 serves several important functions including attenuation of pressure (shock) waves (discussed below), creates a barrier within external housing body 16 to prevent a flame front from bypassing canister 32, and forms the structure which retains canister 32 in its transverse orientation within external housing 16. With reference to FIG. 2 taken in combination with FIG. 7, a plurality of holes are drilled around the annular circumference of ring-shaped bulkhead 42 in order to receive a plurality of bolts, collectively 44, which thread into canister flange 38. Bolts 44, threaded into canister flange 38, retain canister 32 in its transverse orientation within external housing 16 of flame arrestor 10. Bolts 44 may be lock wired as to prevent them from working loose and causing a failure.

Canister flange 38 is likewise ring-shaped, however, canister flange 38 has a smaller diameter than bulkhead 42 in its preferred embodiment. Canister flange 38 is preferably drilled and tapped with holes around its bottom annular surface such that the holes match the holes drilled through bulkhead 42. The holes drilled in canister flange 38 are tapped with threads which mate the threads of bolts 44. Moreover, the holes drilled and tapped in canister flange 38 do not extend entirely through canister flange 38 in the preferred embodiment in order to prevent gas, or more significantly a flame front, from escaping into outlet port 18 around bolts 44. The width of ring-shaped canister flange 38, in the preferred embodiment, is approximately equal to the space formed between outer housing 34 and inner housing 36 which retains expanded metal media 40, plus the width of outer housing 34 and inner housing 36 which are welded onto canister flange 38.

Both canister flange 38 and bulkhead 42 are ring-shaped and include concentric holes 46 and 48 machined through the center of canister flange 38 and bulkhead 42, respectively. The size of concentric holes 46 and 48 is approximately the same size or greater as the internal diameter of inner cylinder 36. The purpose of concentric holes 46 and 48 is to allow the unrestricted passage of gas exiting canister 32 through the inside of inner cylinder 36 to exit the inside of inner cylinder 36 and into outlet port 18 to then exit flame arrestor 10 through outlet flange 20 and into the outbound pipeline (as illustrated by the arrows in FIG. 12).

With specific reference to FIGS. 2, 5 and 7, the construction of outer cylinder 34 shall next be described. Outer cylinder 34 includes, generally, a domed cap 50, a first weld ring 52, a second weld ring 54, a transition point/attenuation matrix 56 which may be coiled between first weld ring 52 and second weld ring 54, and a plurality of support ribs, collectively 56 which bound the outer circumference of outer cylinder 34. In the alternative, transition point/attenuation matrix 56 may include a series of annular rings, each spaced according to the known MESG of the gas application and positioned between first weld ring 52 and second weld ring 54.

Weld ring 52 is welded to domed face 50 while weld ring 54 is welded to canister flange 38. Transition point/attenuation matrix 56 is in a preferred arrangement depicted in FIGS. 4, 5, 6A, and 6B a helical wound wire with a tapered (wedge) shape. Helical wedge wire 56 is a continuous helical winding from first weld ring 52 to second weld ring 54. Helical wire 56 of the preferred embodiment is defined by a blunt surface 62 and tapered surfaces 60 which intersect at a point 61. Port 61 where tapered (wedge) surfaces 60 intersect is spot welded in the preferred embodiment to support rods 58 to form the outer circumference of outer cylinder 34. The helical wire which forms transition point/attenuation matrix 56 of the preferred embodiment is such that gas entering canister 32 will impinge blunt surface 62 causing turbulent gas flow. The ends of support rods 58 are welded to first weld ring 52 and second weld ring 54 respectively. Accordingly, a unitary, substantially cylindrical outer cylinder 34 is described.

Likewise, inner cylinder 36 includes a domed face 64, a transition point attenuation matrix 66, and support ribs, collectively 68. Ribs 68 are identified in FIG. 6A and 6B collectively and representative rib 68 is identified in FIGS. 4, 6A, 6B and 7. Inner cylinder 36 also includes a first weld ring 70 in FIG. 6A and FIG. 6B and FIG. 7 which is welded to domed face 66 and a second weld ring 73 (FIG. 7) which is welded to canister flange 38. The ends of support ribs 68 are welded to weld rings 70 and 73. In the preferred embodiment, a helical wedge wire 66 is a continuous helical winding between weld rings 70 and 73. Point 71 where tapered surfaces 72 intersect is spot welded to support ribs 68 to form the inner circumference of inner cylinder 36.

Both outer cylinder 34 and inner cylinder 36 of canister 32 include a transition point/attenuation matrix which forms their respective cylindrical circumferences. The transition point/attenuation matrix 56 of outer cylinder 34 and transition point/attenuation matrix 66 of inner cylinder 36 are preferably helical or parallel wedge (FIG. 14) wire or rings (FIG. 15). The wire preferably having a tapered surface and a blunt (flat) surface (FIG. 14). As depicted in FIG. 6A and FIG. 6B, transition point/attenuation matrix 56 preferably includes tapered surfaces 60 which intersect at point 61 such that point 61 on the circumference of outer cylinder 34 points towards the center of canister 32. In contrast, transition point/attenuation matrix 66 preferably includes tapered surfaces 72 which intersect at point 71 such that point 71 on the circumference of inner cylinder 36 points also points towards the center of canister 32. The blunt surfaces of the transition point/attenuation matrix of both outer cylinder 34 and inner cylinder 36 of canister 32 abut the flow of gas regardless of which direction it is flowing. As a result, the flame arrestor device of the present disclosure is bi-directional. As stated, in the alternative, the transition point/attenuation matrices could be square or rectangular wire shown in cross-section as 57 and 67 in FIG. 15. Blunt surfaces 62 and 74 to create turbulent gas flow are also present in this embodiment. Additionally, the transition point/attenuation matrix could be configured as rings in either wedge or square (rectangular) geometries.

Inner cylinder 36 is of a smaller diameter than outer cylinder 34 such that when canister 32 is assembled, inner cylinder 36 fits inside outer cylinder 34 with a torturous path media 40 bounded by and retained between the tapered surfaces 60 of the transition point/attenuation matrix 56 of outer cylinder 34 and the tapered surfaces 72 of the transition point/attenuation matrix 66 of inner cylinder 36 in a preferred arrangement.

Helical wedge shaped wire screen which forms transition point/attenuation matrix 66 in the preferred embodiment of inner cylinder 36 includes a blunt surface 74 and tapered surfaces 72 which terminates at point 71. As can be seen in FIGS. 4, 5, 6A, and 6B, the tapered surfaces 72 of helical wedge shaped wire screen 66 of inner cylinder 64 are oriented in the opposite manner of transition point/attenuation matrix 56 of outer cylinder 34 such that tapered surfaces 72 of helical wound wedge wire screen 66 of inner cylinder 36 points away from the center of inner cylinder 36 while the tapered surface 60 of helical wound wedge wire screen 56 of outer cylinder 34 points toward the inside of outer cylinder 34. The helical wound wedge wire screen 56 and 66 of outer cylinder 34 and inner cylinder 36, respectively, in the preferred embodiment is Vee-Wire® screen commercially available from USF Johnson Screens, 1950 Old Hwy NW, New Brighton, Minn. 55112.

The geometry of the wire forming the transition point/attenuation matrix 56 of the outer cylinder 34 and transition point/attenuation matrix 66 of inner cylinder 36 serve the dual purposes of disrupting or providing turbulent gas flow characteristics through canister 32 and also traps debris and contaminants between adjacent windings of outer cylinder 34 and inner cylinder 36, respectively. Debris and contaminants trapped between respective adjacent windings can be easily removed in order to restore flow (reduce pressure drop) through canister 32 in a manner described below.

Turbulent gas flow into and through canister 32 past transition point attenuation matrix 56 of outer cylinder 34 and transition point attenuation matrix 66 of inner cylinder 36 occurs as result of gas flow being disrupted as a result of impact with blunt surface 62 of transition point/attenuation matrix 56 as it flows into canister 32 and contact with blunt surface 74 of transition point/attenuation matrix 66 as the gas flows out of inner cylinder 36 of canister 32 while causing minimal pressure drop. This is because blunt surface 62 of transition point/attenuation matrix 56 and blunt surface 74 of transition point/attenuation matrix 66 cause an increase in the turbulence of the gas passing thereby as a result, increased turbulence correlates to increased heat transfer to the tortuous path media 78 and 86. This is depicted in FIGS. 14 and 15. Additionally, the length of the transition point/attenuation matrix 56 and thereby canister 32 can be varied to accommodate a larger volume of gas to minimize pressure drop.

The size of the gaps between adjacent windings of the respective blunt surfaces 62 and 74 of transition point/attenuation matrices 56 on outer cylinder 34 and 66 on inner cylinder 36 aid in extinguishing a flame passing therethrough according to the known MESG characteristics of a selected gas application. Accordingly, a gap size can be selected depending upon the type of gas to be carried by a certain gas piping system application. For the purposes of exemplification, the known MESG for hydrogen is 0.102 mm or 0.004 in. In an example hydrogen gas application, the gap size between adjacent windings of the blunt surfaces 62 and 74 of transition point/attenuation matrices 56 and 66, respectively would be sized so as to gain a significant increase in the velocity and a decrease in pressure of the pressure front causing increased turbulence and greater resident time. In a hydrogen application, a gap size larger than the MESG has been found to be acceptable. Accordingly, the gap dimension measured between adjacent blunt surfaces 62 and 74 of adjacent windings of transition point/attenuation matrices 56 and 66, respectively, serve the additional significant function of increasing the velocity and a decreasing pressure of the pressure front causing increased turbulence and an even greater resident time. aiding to extinguishing a flame front.

The helical design of the preferred embodiment transition point/attenuation matrix 56 of outer cylinder 34 and transition point/attenuation matrix 66 of inner cylinder 36 is intended to provide a cost effective means of manufacture of a flame arrestor canister such that the gap size between adjacent blunt surfaces 62 and 74 of screen 66 can be consistently and accurately maintained.

FIG. 4 is a cutaway view taken along line 4-4 of FIG. 1. FIG. 4 depicts outer housing 16 with cap 24 secured thereto via nuts 28 secured by bolts 30, collectively. Outer cylinder 34 and inner cylinder 36 are also depicted with torturous path media 40 contained therein. Outer cylinder 34 is depicted showing helical wedge wire 56 as welded to support rods 58. Likewise, inner cylinder 36 is depicted with helical wedge wire 66 welded to support rods 68.

Next referring to FIGS. 2, 6A, 8A, and 8B, in a preferred embodiment, torturous path media 40 consists of layers (by rolling tightly) expanded metal 76. An alternate preferred embodiment (FIGS. 6B, 9, 10, 11A, and 11B) employs stacked metal cones 86. Other readily available materials like sintered metal foam, perforated metal, parallel plates or wire mesh can also be substituted for the expanded metal 76.

The particular torturous path media selected will depend upon the gas application and is dictated by the known MESG of the gas. By way of example, in the environment of a low MESG gas such as hydrogen (0.102 mm), the torturous path formed by rolling expanded metal 76 can be much larger than the MESG of that gas due to the highly turbulent environment created by the combination of the torturous path media 40 and the transition point/attenuation matrices 56 and 66. It is preferred that the spaces between the layers of expanded metal 76 as a result of rolling be approximately 0.102 mm or less in a hydrogen gas environment so as to not negate the effect of the transition point/attenuation matrices 56 and 66 and torturous path media 76 to extinguish a hydrogen gas flame front.

In addition to the flame extinguishing capabilities of the gaps formed between the blunt surfaces 62 and 74 between adjacent windings of helical wound wedge wire screen 56 and 66 of outer cylinder 34 and inner cylinder 36, respectively, blunt surfaces 62 and 74 serve the purpose of containing expanded metal media 40 within canister 32. Torturous path media 40 in the preferred embodiment consists of expanded metal which is available commercially and used extensively in industrial applications. In the preferred embodiment the expanded metal (76 of FIG. 6A) is rolled and inserted between inner cylinder 34 and outer cylinder 36. Expanded metal 76, when rolled, forms internal passageways that are non-linear and thereby define a torturous path for the gas to travel between outer cylinder 34 and inner cylinder 36. This torturous path assists the transition point/attenuation matrices in extinguishing a flame front as it enters and passes through canister 32.

Expanded metal 76 (FIG. 8A and 8B) is defined by lengths, such as 79, 80, 81, 82, 83 and 84 forming diamond shaped sections 86 with an internal passage 85 through the center of each diamond section 86. Multiple diamond sections 86 make up a rolled sheet of “regular expanded metal” 76 that is used in the preferred embodiment. Regular Expanded Metal is a finished product as it comes from the press after having been die cut and expanded. Each sheet that comes off the expander is in standard or regular form with the junctions at the strands and bonds forming a ridge surface. FIG. 8A and FIG. 8B show that the strands and bonds form a sharp angle to the original plane of the solid sheet. Regular expanded metal 76 is available commercially, such as from Alabama Metal Industries Corporation, 3245 Fayette Ave., Birmingham, Ala. 35208 and Metalex Expanded Metal Products, 1530 Aratius Parkway, Libertyville, Ill. 60048 and formed by piercing a sheet of thin material, most commonly 316 stainless steel, carbon steel, aluminum and even plastics.

When rolled tightly and inserted into canister 32 between inner cylinder and outer cylinder (FIG. 6A), expanded metal media 76 creates a torturous path for the gas, or more particularly a flame front, to travel in order to pass through flame arrestor 10. The blunt faces 62 and 74 of transition point/attenuation matrices 56 and 66, respectively (FIG. 14), together with the torturous path created by rolled expanded metal media 76 disrupts the laminar flow of a flame front (creates turbulence and increases residence time). Moreover, in addition to increasing turbulence and increasing residence time, the combination of transition point/attenuation matrices 56 and 66 together with a torturous path media such as expanded metal 76 provides substantial surface area for the flame/gas to contact. The turbulence created and the increased residence time created by the transition point/attenuation matrices 56 and 66 have superior heat transfer characteristics to the heat sink (expanded metal 76 torturous path media) than conventional laminar flow matrixes. The turbulence created as well as the heat sink created by the substantial surface area act to extinguish a flame passing through canister 32. Canister 32, including expanded metal 76 torturous path media contained therein, is designed to provide an optimum pressure drop per unit volume to provide maximum flame arrestment. Again, as a result of the transverse design, the aggregate pressure drop resulting from the passage of the gas through canister 32 can be maintained at a low value by varying the length of the canister 32 (and housing 16—FIG. 2) as required.

With reference to FIG. 2 taken in combination with FIGS. 5 and 6, the entire space formed between inner cylinder 36 and outer cylinder 34 is filled with torturous path media 40 and retained between blunt transition point/attenuation matrix 56 of outer cylinder 34 transition point/attenuation matrix 66 of inner cylinder 36.

With reference to FIGS. 9, 10, 11A, and 11B, in an alternate preferred embodiment torturous path media is disclosed. In this alternate preferred embodiment, an array of stacked metal cones 86 are substituted for the expanded metal and inserted into canister 32 between outer cylinder 34 and inner cylinder 36. FIG. 9 depicts the flame arrestor 10 of the present disclosure which includes a canister 32 including a stacked metal cone 86 torturous path media.

With specific reference to FIGS. 11A and 11B, an exemplary array of stacked cone media 86 is depicted. Each cone, such as exemplary cone 100 is truncated so as to provide a center hole which is slightly larger than the diameter of inner cylinder 36 (FIG. 10). Each truncated cone of stacked array 86 such as cone 100 includes a plurality of spacers, collectively 102, disposed on its outer conical surface. When stacked in array 86, spacers 102 provide a space or gap between adjacent cones in the stacked array. These spaces can be varied according to the thickness of spacers 102. The spaces between adjacent cones in stacked array 86 allow the passage of gas therethrough as the gas passes through canister 32 (FIG. 9 and FIG. 10). The size of the space or gap may be selected according to the known MESG of the gas in the piping application.

Referring to FIG. 10, canister 32 may be constructed using the array of stacked cones 86 positioned between outer cylinder 34 and inner cylinder 36. In this alternate preferred embodiment, array of stacked cones 86 is inserted between outer cylinder 34 and inner cylinder 36 with the gaps or spaces described above between adjacent individual cones. A cone retainer 94, which is a ring having an angled edge which mates the angle of the array of stacked cones 86 is placed above or on top of stacked cone array 86. A compressor 92 which may be a pipe sleeve contacts retainer 94. In this alternate preferred embodiment, domed cap 90 is welded to compressor 92 and serves the function of cap 64 of FIG. 7. An outer domed cap 93 including a central opening through which cap 90 extends is fitted over domed cap 90 and welded to a weld ring 98 and to compressor 92 so as to seal the interior of the upper space between outer cylinder 34 and inner cylinder 36. Weld ring 98 is welded to the transition point/attenuation matrix which comprises the exterior of outer cylinder 34. Likewise, the transition point/attenuation matrix comprising the surface of inner cylinder 36 may be welded to compressor 92. At the lower segment of canister 32 in this alternate preferred embodiment, a weld ring 98 is welded to the transition point/attenuation matrix which forms inner cylinder 36 and also welded to canister flange 38 so as to seal the interior of canister 32. Canister flange 38 is bolted to bulkhead 42 as described above so that canister 32 may be secured within external housing 16 (FIG. 9).

When installed between outer cylinder 34 and inner cylinder 36 of canister 32, as depicted in FIG. 6B, stacked cone media 86 creates a torturous path for the gas, or more particularly a flame front, to travel in order to pass through flame arrestor 10. Transition point/attenuation matrices 56 and 66 fanning outer cylinder 34 and inner cylinder 36, respectively, together with the torturous path created by stacked cone media 86 disrupts the flow of a flame front and creates turbulence as well as increasing the residence time of the gas/flame front within canister 32. In addition to increasing the turbulence and increasing residence time, the combination of transition point/attenuation matrices 56 and 66 together with a torturous path media such as stacked cone array 86 provides substantial surface area for the flame/gas to contact. The turbulence created, as well as the heat sink created by the substantial surface area and increased residence time act to extinguish a flame passing through canister 32 including stacked cone array 86. Canister 32, including stacked cone array 86 contained therein, is designed to provide an optimum pressure drop per unit volume to provide maximum flame arrestment. As set forth above, as a result of the transverse design of the present disclosure, the aggregate pressure drop resulting from the passage of the flame/gas through canister 32 can be maintained at a low value by varying the length of canister 32 which can be accomplished by increasing the number of stacked cones in array 86 as required.

With reference to FIG. 6A and FIG. 6B, debris (contaminants) carried in the gas stream, collectively 96, may be trapped between adjacent windings of transition point/attenuation matrix 56 of outer cylinder 34. Trapped debris 96 can be easily dislodged upon application of a reverse flow within the canister by injecting a high pressure cleaning solution into torturous path metal media 40 from above through domed cap 24 of outer housing 16 or below through access port 21. In a particular embodiment, fittings could be placed within torturous path media 40 to allow connection of a source of high pressure cleaning solution to be injected directly into torturous path media 40 through domed face 50 dome cap 24 or through canister flange 38 and blank flange 22 (via access port 21). Likewise, any debris which may become trapped between adjacent windings of transition point/attenuation matrix 66 of inner cylinder 36 may be dislodged by the flow from the injection of the high pressure cleaning solution as described above.

Torturous path media 40 can be replaced or recharged by removing canister 32 from outer housing 16 of flame arrestor 10 by removing bolts 30 from domed cap 24 of outer housing 16. With cap 24 removed, canister 32 can be accessed and removed by removing blank flange 22 which accesses the interior of outer housing 16. Bolts 44 may then be removed through access opening 21 such that canister flange 38 is disconnected from bulkhead 42. Canister 32 is then free for removal from outer housing 16. A new canister can be installed in outer housing 16, or, alternatively cleaned by placed the canister 32 in a bucket or container of cleaning solution or solvent and placed on an “Ultrasonic Cleaning Device”. Canister 32 may then be reinstalled (or a new canister installed) in outer housing 16 and canister flange 38 bolted to bulkhead 42. Domed cap 24 may next be bolted back on to outer housing 16. Blank flange 22 is then bolted to outer housing 16 to seal outer housing 16 and flame arrestor 10 returned to service.

In the event of a change in the type of gas in the piping system, torturous path media 40 could be removed and replaced with a torturous path media of a component diameter which is suitable for the new gas application. This could be accomplished by removal and replacement of canister 32 as described above.

The direction of flow of gas in FIG. 12 is illustrated by arrows entering the external housing through inlet flange 12, passing through inlet port 14 around canister 32 between canister 32 and the inside of external housing body 16, turning abruptly into and through to the center of canister 32, and turning again abruptly out of canister 32 into outlet port 18 and then exiting through outlet flange 20.

Canister 32 is secured to bulkhead 42 in the transverse orientation described above in order that a pressure wave front (shock wave) which passes through the piping system as a result of a detonation of the gas contained in the piping system will enter flame arrestor 10 through inlet flange 12 and inlet port 14. The shock wave will then impinge domed face 50 of outer cylinder 34 and will also pass into the space defined between external housing body 16 and outer cylinder 34 and impact bulkhead 42. Both bulkhead 42 and domed face 50 of outer cylinder 34 are constructed to withstand the force of an impinging shock wave. The detonation wave front (shock wave) is thereby attenuated by the combination of domed face 50 of the outer cylinder 34 and bulkhead 42.

As stated previously, flame arrestor 10 is bi-directional. The direction of flow of gas in FIG. 13 is in the reverse direction from that of FIG. 12. Flow in the reverse direction is illustrated by arrows entering external housing 16 through outlet flange 20, passing through outlet port 18 and into inner cylinder 36 of canister 32 via concentric holes 46 and 48 past transition point/attenuation matrix 66. Gas flow then turns abruptly into and through torturous path media 40, and turning again abruptly out of canister 32 through transition point/attenuation matrix 56 and into inlet port 14 to exit through inlet flange 12.

Likewise, a pressure front which may be directed upstream in the piping system back toward flame arrestor 10 or which has passed through flame arrestor 10 even though the flame front is extinguished, that may be directed or reflected back into flame arrestor 10 through outer flange 20, outer port 18 and back into canister 32 will be attenuated by the structural integrity of the inside surface of domed face 64 of inner cylinder 36 without causing damage to canister 32 or the external housing of flame arrestor 10. The transverse orientation of canister 32 within the outer housing of flame arrestor 10 allows the structural integrity of canister 32 to absorb a pressure front (shock wave) or reflected pressure front.

While the invention has been described with a certain degree of particularity, it is manifest that many changes may be made in the details of construction without departing from the spirit and scope of this disclosure. It is understood that the invention is not limited to the embodiment set forth herein for purposes of exemplification, but is to be limited only by the scope of the attached claim or claims, including the full range of equivalency to which each element thereof is entitled. 

1. A detonation flame arrestor canister supported within an external housing, comprising: an inner cylinder including a first end, a second end, an outer circumference, and an outer diameter; said first end of said inner cylinder is supported from said external housing; an outer cylinder including a first end, a second end, an outer circumference, and an inner diameter; said inner diameter of said outer cylinder being larger than said outer diameter of said inner cylinder such that a space is formed between said inner cylinder and said outer cylinder when said outer cylinder is placed over said inner cylinder; said first end of said outer cylinder is supported from the external housing; at least a portion of said outer circumference of said outer cylinder being defined by a transition point/attenuation matrix; at least a portion of said outer circumference of said inner cylinder being perforated to allow a gas to pass through said perforated portion; a torturous path media disposed in said space between said inner cylinder and said outer cylinder.
 2. The canister of claim 1 wherein said transition point/attenuation matrix of said outer cylinder is wedge shaped wire.
 3. The canister of claim 2 wherein said transition point/attenuation matrix of said outer cylinder is helical wedge shaped wire.
 4. The canister of claim 2 wherein said transition point/attenuation matrix of said outer cylinder is parallel wedge shaped wire.
 5. The canister of claim 1 wherein said transition point/attenuation matrix of said outer cylinder is ring wire.
 6. The canister of claim 5 wherein said transition point/attenuation matrix of said outer cylinder is helical ring wire.
 7. The canister of claim 5 wherein said transition point/attenuation matrix of said outer cylinder is parallel ring wire.
 8. The canister of claim 1 wherein said perforated portion of said inner cylinder is defined by a transition point/attenuation matrix.
 9. The canister of claim 8 wherein said transition point/attenuation matrix of said inner cylinder is wedge shaped wire.
 10. The canister of claim 9 wherein said transition point/attenuation matrix of said inner cylinder is helical wedge shaped wire.
 11. The canister of claim 9 wherein said transition point/attenuation matrix of said inner cylinder is parallel wedge shaped wire.
 12. The canister of claim 8 wherein said transition point/attenuation matrix of said inner cylinder is ring wire.
 13. The canister of claim 12 wherein said transition point/attenuation matrix of said inner cylinder is helical ring wire.
 14. The canister of claim 12 wherein said transition point/attenuation matrix of said inner cylinder is parallel ring wire.
 15. The canister of claim 1 used in association with a gas having a known MESG wherein said transition point/attenuation matrix of said outer cylinder is comprised of coiled adjacent windings of wedge or ring wire such that the gap between said coiled adjacent windings of wedge wire is sized so as to increase velocity and decrease pressure of the shock wave in association with the known MESG of said gas.
 16. The canister of claim 1 wherein said torturous path media is rolled expanded metal.
 17. The canister of claim 1 wherein said torturous path media is a plurality of stacked cones.
 18. The canister of claim 1 wherein said torturous path media is tightly and fully filling said space between said inner cylinder and said outer cylinder.
 19. A detonation flame arrestor canister supported within an external housing, comprising: a canister flange supported within the external housing; an inner cylinder including a first end, a second end, an outer circumference, and an outer diameter; said first end of said inner cylinder is supported from said canister flange; said second end of said canister flange is sealed; an outer cylinder including a first end, a second end, an outer circumference, and an inner diameter; said inner diameter of said outer cylinder being larger than said outer diameter of said inner cylinder such that a space is formed between said inner cylinder and said outer cylinder when said outer cylinder is placed over said inner cylinder; said first end of said outer cylinder is supported from said canister flange; at least a portion of said outer circumference of said outer cylinder being defined by a helical wedge shaped wire screen; at least a portion of said outer circumference of said inner cylinder being defined by a helical wedge shaped wire screen; a rolled expanded metal or stacked cone media contained in said space formed between said inner cylinder and said outer cylinder.
 20. The canister of claim 19 used in association with gas having a known MESG wherein said helical wedge shaped wire screen of at least said outer cylinder is comprised of coiled adjacent windings of wedge shaped wire such that the gap between said coiled adjacent windings of wedge shaped wire is sized so as to coincide with said known MESG.
 21. A detonation flame arrestor, comprising: an external housing; said external housing including an inlet and an outlet each having concentric longitudinal axes; a canister supported in said external housing, said canister comprising: a) an inner cylinder including an outer circumference and an outer diameter; b) said inner cylinder supported from said external housing; c) an outer cylinder including an outer circumference and an inner diameter; d) said inner diameter of said outer cylinder being larger than said outer diameter of said inner cylinder such that a space is formed between said inner cylinder and said outer cylinder when said outer cylinder is placed over said inner cylinder; e) said outer cylinder supported from the external housing; f) at least a portion of said outer circumference of said outer cylinder being defined by a transition point/attenuation matrix; g) at least a portion of said outer circumference of said inner cylinder being defined by a transition point/attenuation matrix; h) a torturous path media disposed in said space between said inner cylinder and said outer cylinder, wherein said canister includes a longitudinal axis which is offset from said longitudinal axes of said inlet and said outlet of said external housing.
 22. The detonation flame arrestor of claim 21 wherein said longitudinal axis of said canister is transverse to said longitudinal axes of said inlet and said outlet of said external housing.
 23. The detonation flame arrestor of claim 22 wherein said external housing includes at least one removable port to access said canister.
 24. The detonation flame arrestor of claim 23 wherein said canister includes a top end and a bottom end and said external housing includes an access port adjacent said top end and said bottom end of said canister. 